In EP-A1-0,306,568 are disclosed a method and apparatus for applying liquid medium to web or sheet material, particularly for patterning material such as woven or tufted web material such as carpet fabric and tiles. The apparatus comprises a row of jets each of which is controlled by an electro-mechanical valve. The material is passed beneath the jets which fire discrete liquid droplets directly at the material when the valves open and close under the control of a computer. Several such rows can be provided to apply multiple colours.
The jets comprise hollow needles or capillary tubes which have a bore diameter of from 0.2 mm to 2 mm and operate to fire the liquid in pulses of 0.5 to 15 milliseconds, the duration being varied to match other parameters such as the pressure of the liquid and its viscosity, the speed of passage of the material and the extent of the area desired to be covered by each pulse.
While the apparatus as is described in EP-A1-0,306,568 is eminently suitable for the printing of patterns such as are appropriate to carpets and carpet tiles and at reasonable speeds in comparison to other, conventional ways of patterning such items, it is not readily capable of being adapted to printing fine detail such as is required on apparel fabrics and some household fabrics for curtains, upholstery and the like, nor to operate at speeds commensurate with conventional methods for colouring such fabrics.